The purpose of this research project is to study the structure and function of cytoskeletal proteins. Two major cytoskeletal proteins, desmin and vimentin, from hamster fibroblasts have been purified. Antisera against these proteins have been used to probe the organization of these proteins in fibroblasts and other tissues. The results so for indicate that both desmin and vimentin in normal cultured fibroblasts, BHK21/C13' are both present in the 10 nm filament system of the cell. Other cell systems have been studied for the presence of these two proteins. Platelets contain similar proteins and also platelet cytoskeletons possess a great deal of blood coagulation activity. The possible correlation between these two findings is being investigated.